Energy production from renewable sources—primarily solar, wind, and geothermal—continues to increase in importance as conventional fossil fuel energy sources become less abundant and concerns about carbon dioxide and other products of combustion grow. Renewable energy production is particularly important for areas of the world where power distribution infrastructure is not fully developed.
Renewable energy production involves myriad technological challenges. One of the most fundamental challenges is that renewable energy production is usually not constant or at a steady rate. For example, the amount of power produced by a solar panel will vary with the latitude, the time of day, the inclination of the panels relative to the sun, the weather, the age of the panels, and other factors. For that reason, most renewable energy production systems include some kind of battery or batteries to store power as it is produced and to allow it to be used at other times.
As chemical repositories of energy, batteries have their own difficulties. Most types of batteries do not respond well to frequent charge-discharge cycles. Lithium ion batteries, which are popular in consumer electronics, have a high energy density and can withstand repeated charge-discharge cycles, but are susceptible to the memory effect, and are also expensive. Lead-acid batteries, by contrast, are ubiquitous (they are used in automobiles), but can begin to oxidize and may suffer permanent damage if they are allowed to fully discharge.
If renewable energy production is to reach its full potential, better technologies for maintaining battery condition and charge, for providing power at more constant voltage and current levels, and for managing appliances connected to non-constant power sources are needed.